This invention relates to a D.C. rotary machine, and more particularly to such a D.C. rotary machine which is provided with interpole compensation equipment.
Briefly, a D.C. rotary machine is generally composed of a stator or a field structure, a rotor or an armature, and a commutation structure. The stator includes a yoke of annular shape, a plurality of main poles provided by winding main pole windings respectively around a plurality of main pole cores disposed along the inner peripheral face of the yoke in a relation circumferentially spaced apart by a predetermined distance from each other, and a plurality of interpoles provided by winding interpole windings respectively around a plurality of interpole cores disposed between the plural main poles. The rotor includes an armature core or a rotor core fixedly mounted on a rotary shaft, and an armature winding received in many slots formed in the outer periphery of the rotor cores. The commutation structure includes a commutator fixedly mounted on the rotary shaft, and brushes disposed on the stator side to make slidable contact with the commutator segments for performing the commutation in cooperation with the commutator. The main magnetic flux produced from the main poles is directed toward the armature, and the interpole magnetic flux produced from the interpoles for generating the commutating emf during commutation, in which reversal of the armature current occurs, is also directed toward the armature.
This interpole flux is effective to a certain extent for compensating the non-uniformity of the main magnetic flux distribution attributable to the armature reaction and also to the relative polarities of the main poles and interpoles. Actually, however, the magnetic flux distribution around the interpole is frequently unsymmetrical with respect to the circumferential center of the interpole.
In order to prevent this unsymmetrical magnetic flux distribution, the interpole compensation windings are usually wound around a plurality of interpole cores.
A D.C. rotary machine of this type has been disclosed, for example, in Japanese Patent Publication No. 46299/82.
With the D.C. rotary machine having such as conventional interpole compensation windings, however, sparks generated at the commutation starting side and the commutation ending side can not be compensated thereby, that is, when a no-spark zone is immigrated from the previous setting zone to the others, the conventional D.C. rotary machine can not compensate the commutating electromotive force (emf) during commutation corresponding to the immigration of the no-spark zone.